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Police later said they don't believe the assault was targeted because he was white.

Chicago area police said on Thursday that formal charges, including hate crime and battery related, were filed against the four black suspects, according to the Associated Press.

Guglielmi said the suspects made "terrible racist statements" during the attack, but that investigators believe the victim was targeted because he has special needs, not because of his race.

Guglielmi said it's possible the suspects were trying to extort something from the victim's family.

Video from Chicago media outlets appears to show someone off-camera using profanities about "white people" and President-elect Donald Trump. Chicago Police Superintendent Eddie Johnson said Wednesday that the victim has mental health challenges, and he called the video "sickening."

Guglielmi said police are working with prosecutors "to build the strongest case."

The 18-year-old man who was injured in the video was reported missing Monday from a Chicago suburb. His parents said they received text messages from the people who claimed to have kidnapped their son.

After police looked into the messages, the live streamed video was discovered.

In the video, the attackers can also be heard making politically and racially charged statements towards the man. They even go on to further threaten the man and at one point someone can be heard saying they were going to put the man into the trunk of a car and “put a brick on the gas and let the engine ----.”

WARNING: Some might consider the contents of this video to be graphic in nature.

The victim was later found by police wandering the streets Tuesday afternoon and taken to a nearby hospital.

Captain Steven Sesso said “At the same time, there were some individuals from another incident that were taken into custody at roughly the same address.”

Supt Johnson said “Thanks to the outstanding work of 11th district police officers and area north detectives, all four offenders from the incident are in police custody and awaiting formal charges."

The grandmother of a young woman associated with the live video says her granddaughter "had her ups and downs," but is "a good person."

Priscilla Covington of Chicago says she raised the young woman "since she was a baby."

She says her granddaughter no longer lives at the family home but still lives in Chicago.

The grandmother says the video doesn't reflect the young woman she raised.

She says she's worried because her family, including the woman's younger sisters, have been threatened since the video was posted online.

She says she saw and talked to her granddaughter about four days ago, and "she was OK."

Authorities say the victim knew at least one of the accused attackers but officials are still trying to determine a motive.